Referee “Big” John McCarthy will be conspicuously absent from UFC 104 this Saturday at the Staples Center in Los Angeles. The 15-year officiating veteran, who’s logged in nearly 600 fights worldwide dating back to UFC 2 and has a long background in helping shape the sport’s current rules, was not assigned by the California State Athletic Commission to work the event.

McCarthy, a California native, has been re-licensed in the state since November 2008, after returning from a yearlong retirement to pursue broadcasting opportunities. McCarthy has refereed and judged at multiple events in California this year.

McCarthy was also informed in mid-September that his application to referee fights in Nevada would be placed in a “pending” file by the Nevada State Athletic Commission. NSAC Executive Director Keith Kizer said the state had no space for McCarthy at this time.

However, that decision has prompted public comment speculating if McCarthy’s departure from officiating UFC events in late 2007 to work with rival promotions like Affliction as a commentator, along with statements he made while in that position, are being held against him.

“I contacted (the CSAC) and told them I was free on Oct. 24,” McCarthy told Sherdog.com Friday. McCarthy said he was later informed that he hadn’t been assigned to the event, the UFC’s first in California since UFC 76 in November 2007. McCarthy did not comment any further on the development.

Dave Thornton, interim executive officer of the California State Athletic Commission, replied to an email request from Sherdog last Thursday inquiring about criteria for referees to officiate UFCs and how those officials are selected to work shows.

“McCarthy is a licensed referee in California and as such is on our regular rotation list for MMA refs,” Thornton wrote. “McCarthy is assigned to a Strikeforce show in November in Fresno.”

Follow-up inquiries were sent Thursday and Monday to the CSAC’s Thornton asking for more specific criteria about who is assigned to referee UFCs, if McCarthy met the criteria, as well as which referees have been assigned to UFC 104. Those inquiries were not answered as of press time late Tuesday.